This is a proposal for a study of the role of patient preferences and other factors in choices regarding use of prenatal screening for and diagnosis Of chromosomal disorders in a racially/ethnically diverse population. We propose to explore the distribution of prenatal screening and diagnosis choices made at our institution, which serves a racially/ethnically and socioeconomically diverse population. We also will collect detailed information regarding the distribution of individual preferences for test characteristics and outcomes by racial/ethnic group, as well as other factors which may be related to choices regarding the use of these tests. These data will be collected from women in the obstetrics clinics, to capture the preferences of all pregnant women who will be 35 or older at the time of delivery, not just those who attend genetic counseling. State-of-the-art preference measurement methods, including visual analog scaling and the standard gamble, will be used to elicit preferences from women who are facing a decision to undergo-or forgo-testing, and which test to use. Using both decision-analytic and regression techniques, we will compare "predicted" choices (based on expected utility theory) to actual choices made, and we will analyze the contribution of patient preferences and other factors in the choices we observe. We also will explore the cost effectiveness of current and proposed age- and risk-based guidelines for prenatal testing, and compare them to the estimated cost effectiveness of a reference-based guideline. Information generated in this study will ultimately be used in the development of a decision-assisting technology to help women of diverse backgrounds make informed choices regarding testing that reflect their underlying preferences, and in the delineation of guidelines for use of prenatal diagnostic services that place greater emphasis on patient presences and values, in addition to risk.